Effect of screening current on the electro-magnetic-force characteristics of high-field no-insulated coils

Abstract

No-insulation (NI) superconducting coils have emerged as a critical area of research for attaining elevated magnetic fields, owing to their remarkable stability and quench resistance. This study introduces a novel model for azimuthal current characterization, utilizing an enhanced T–A formulation in conjunction with the weak-form finite element method. By establishing a numerical model corresponding to the 32 T double-inserted high-field coil experimental setup at the National High Magnetic Field Laboratory, the influence mechanism of screening current on the electromagnetic and mechanical properties of the coil during excitation is systematically analyzed. The results demonstrated that, compared to the traditional insulated (INS) superconducting coils, the NI coil exhibits reduced screening currents and vertical screening current-induced fields (SCIFs) when the central magnetic field reaches its peak. Notably, the vertical-induced magnetic field plays a dominant role in the distribution of SCIF. The stress–strain analysis obtained employing a subregion-coupled modeling approach reveals that the screening current-induced stress in NI coils is lower than that in INS coils. This finding fully validates the performance advantages of NI coils when operated in ultrahigh field conditions. This study provides new insights and methodologies for the research and application of NI coils in high-field magnet systems.